A power management system may attempt to efficiently direct power to different components of a computing device, and may be especially important for portable computing devices that rely on battery power. For example, by reducing power to components that are not being used, a power management system may increase the lifetime of a battery.
Advanced Configuration and Power Interface (ACPI) is a specification that establishes interfaces for operating system directed configuration and power management on laptops, desktops, servers, and other systems. ACPI defines power and configuration management interfaces between an operating system and firmware, such as, a basic input/output system (BIOS).
The ACPI specification includes an ACPI Source Language (ASL) in which system designers may describe the operations of a power management system. ASL code may be compiled into an ACPI Machine Language (AML) which is in a binary pseudo-code format that can be parsed by an ACPI AML interpreter coupled to an operating system. Further details of the ACPI specification may be found in “Advanced Configuration and Power Interface specification”, Revision 3.0, published on Sep. 2, 2004 at “www.acpi.info”.
The Extensible Firmware Interface (EFI) is a specification that defines a model for an interface between an operating system and platform firmware, such as, BIOS. The EFI includes data tables comprising platform-related information, in addition to boot and runtime service calls that are available to an operating system and an operating system loader. Further details of the EFI specification may be found in the publication “Extensible Firmware Interface Specification,” version 1.10, published on Dec. 1, 2002 by INTEL* Corporation.